Starting and controlling apparatus for electric discharge lamps



April 1, 1947. H. cAMpBgLL 2,418,161

STARTING AND JONT ROLLING APPARATUS FOR ELECTRIC DISCHARGE LAMPS Filed Dec. 51, 1943 Inventor: John H. Campbell,

9 HIS Attorney.

Patented Apr. 1, 1947 STARTING AND CONTBOLLIN G APPARATUS FOR ELECTRIC DISCHARGE LAMPS John H. Campbell, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 31, 1943. Serial No. 516,420

3 Claims.

My invention relates to apparatus for starting and controlling electric discharge devices such as discharge lamps of the fluorescent type. As is well known, discharge lamps require a higher voltage for starting than for their subsequent operation. Such lamps in common use at the present time have filamentary electrodes and have apparatus associated therewith by which heating current is passed through the electrodes to heat them to an electron emitting temperature before the starting voltage is applied thereto. As a result of recent developments in the construction of such lamp electrodes the lamps may be started without prior heating of the electrodes, that is, started cold cathode without serious injury to the electrodes. It is the object of my invention to provide improved apparatus for producing the voltage necessary to efiect the starting of such lamps without preheating their electrodes. A further object of my invention is to provide apparatus which while efiective to start a lamp will also control its subsequent operation with the attendant energy losses reduced to a low value.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

Referring to th drawing, Fig. 1 is a circuit diagram illustrating an embodiment of my invention and Fig. 2 is a like diagram illustrating a modification.

Referring first to Fig. 1, two electric discharge devices I and 2 which, for example, may be 40 watt fluorescent lamps of similar construction and of common and well known form each having the filamentary or thermionic electrodes 3, are connected to be operated in parallel from the source of alternating current supply t. The source may be a 60 cycle, 118 volt lighting circuit and the connection therewith is shown controlled by the line switch 5. Connected between the lamp circuits and the source 4 I employ suitable means, such as the autotransformer 6, for stepping up the voltage of the source to a somewhat higher value, for example 330 volts. In the circuit of the lamp 1 is the lamp ballast comprising the reactor l, which for example may have an impedance 750 ohms, and the capacitor 8 which for example may have an impedance of 1610 ohms. The reactor 1 and the capacitor 8 constitute impedance means having a net capacitive reactance. In the circuit of the lamp 21s the lamp ballast comprising the reactor 9, which for example may have an impedance of 710 ohms. In

2 the circuit of the lamp 2 is the lamp ballast comprising the reactor a, which for example may have an impedance of 710 ohms. The reactor t constitutes an impedance means having a net inductive reactance. Thus it will be seen that the net impedance in the circuit of the lamp i is capacitive whereby the lamp current in that circuit is leading and the impedance in the circuit of the lamp 2 is inductive whereby the lamp current in that circuit is lagging. Preferably the impedances in the two-lamp circuits have such values that the total energy taken from the source of supply has a power factor close to unity.

As mentioned above, the lamps which I employ although providedwith thermionic electrodes do not have their electrodes preheated but rather are started cold cathode. I obtain the voltage necessary so to start the lamps in the parallel connected circuits illustrated by means of circuits which constitute means connected intermediate the serially connected reactor and capacitor 8 and the reactor 9, and electrodes of lamps I and 2 and which shunt the lamps and include fixed circuit elements which circuits I shall now describe. Connected across the lamp l is a shunt circuit including the capacitor l0 whose impedance may, for example, be 2650 ohms in series with the reactor II whose impedance may, for example, be 840 ohms. Likewise connected across the lamp 2 is a shunt circuit including the capacitor I2 whose impedance may, for example, be 2650 ohms and the same reactor H in series; thus the reactor is common to the two shunt circuits. The resulting voltages applied to the lamps are sufiicient to cause them immediately to break down upon the closing of the switch 5 after which they continue to operate, the one on a leading current circuit, the other on a lagging current circuit with but slight energy loss in th circuits shunting them.

In the modified form of my invention shown by Fig. 2 I have substituted the reactors l3 and M for the capacitors Ill and I 2 respectively of Fig. 1 and have substituted the capacitor l5 for the reactor ll of that figure, it being understood that the reactances of the substituted members although not the same as the reactances of the members in Fig. 1 for which they are substituted are such that the voltages applied to the lamps when the switch 5 is closed are suflicient to cause the lamps te start. Moreover during their operation but slight energy losses occur in the lamp shunting circuits.

What I claim as new and desire to secure by Letters Patent of the United States is:

'1. In combination, a plurality of reactive lamp circuits each arranged to include an electric discharge lamp having a pair of electrodes, said circuits being connected together to be supplied in parallel from a source of alternating current supply having a voltage less than that required to start the lamps, one of said circuits comprising impedance means having a net capacitive reactance and the other circuit comprising impedance means having a net inductive reactance," and means connected intermediate the first-mentioned and second-mentioned impedance means and electrodes of the lamps and comprising a reactive circuit including a plurality of reactive members including a reactor and a capacitor shunting the lamp in said one circuit and a second reactive circuit including a plurality of reactive members including a reactor and a capacitor shunting the lamp in said othercircuit,

one of said reactive members being common to both said shunt circuits, said reactive shunt circuits and said reactive lamp circuits being operable upon application of current to provide ,high voltage to start said lamps.

2. In combination, a plurality of reactivelamp circuits each arranged to include an electric dischargelamp having a pair of electrodes, said circuits being connected together to be supplied in parallel from a source of alternating current supply having a voltage less than that required to start the lamps, one of saidcircuits comprising impedance means having a net capacitive reactance and the other comprising impedance means having a net inductive reactance, and means connected intermediate the first-mentioned and second-mentioned impedance means and electrodes of thelamp and comprising a capacitively reactive circuit including-a capacitor and a reactor shunting the lamp in said one circuit and a second capacitively reactive circuit including a capacitor and the same reactor shunting the lamp in said 4 other circuit, said reactive shunt circuits and said reactive lamp circuits being operable upon application of current to provide high voltage to start said lamps.

3. In combination, a plurality of reactive lamp circuits each arranged to include an electric dis- .charge lamp having a pair of electrodes, said ing an inductively reactive circuit including a reactor and a capacitor shunting the lamp in said one circuit and a second inductively reactive circuit including a reactor and the same capacitor shunting the lamp in said other circuit, said reactive shunt circuits-and said reactive lamp circuits being operable upon application of current to provide high voltage to start said lamps.

JOHN H. CAMPBELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,314,311 Karash 'Mar. 16,1943 2,298,935 Freeman Oct. 13, 1942 2,361,017 Flick Oct. 24, 1944 2,020,731 Lederer Nov. 12, 1935 2,284,407 Edwards May 26, 1942 2,301,671 Abadie NOV. 10, '1942 2,265,323 Spanner Dec. 9, 1941 

